Continuous lights change after they've been on awhile?!?!

I guess I should've considered this a possibility, but I never thought of it. I just changed the order of my filming session (I put the video first on the docket and photography last, whereas I usually do video last) and the videos look completely different. The shoot takes a couple hours so it's the difference between lights when they are on for a couple hours and when they have just been turned on.

In the latter, the subject's skin tone looks normal - where it looks far "yellower" and more unnatural when the lights have been on awhile.